The minimum money you need to collect will be shown on the start of the level. When you reach that amount you can continue to the next level. Try not to take the stones as much as you can. It will make you lose time and money because they are heavy and worthless, also they will prevent you from collecting gold. Diamonds are the most worthy mines. If you can get them it will be easy for you to move to the next level.
Jerry: "DOWN ARROW KEY"